List Combiner

List Combiner does what it says: two LIST inputs go in, one merged LIST comes out, with elements from list_a kept before elements from list_b. No dedup, no sort, no filtering - it's the simplest possible way to stitch two collections together into a single downstream value.

Where this shows up in practice

This pack leans toward XYZ-plot-style workflows - sweeping a parameter across a grid and collecting results - and those pipelines tend to build their axis values up in pieces. Maybe you've got a handful of checkpoint names selected through Dynamic Checkpoint Selector and a separate hand-picked list from somewhere else, and you want one combined axis to sweep across instead of two disconnected ones. Or you're chaining several sampler or encoder configurations from different parts of a graph and need them collapsed into a single list before something downstream that only accepts one LIST input. List Combiner is the join step for exactly that: two partial lists become one complete one.

Order is preserved and explicit - list_a's items always come first, list_b's second - which matters if whatever consumes the merged list cares about sequence (say, a preview or a labeling step that keys off position rather than value).

The inputs and output

• list_a and list_b (both LIST, required) - the two collections to merge.
• A single LIST output - list_a's contents followed by list_b's.

Worth knowing: LIST here is this pack's own custom type, a Python list carried as a single value - not ComfyUI's native "output is a list" mechanism that auto-executes downstream nodes once per item. Combining two lists with this node doesn't change how many times anything downstream runs; it just changes what data is available in the one combined value.

How to install it

ComfyUI Manager: search DemonAlone-nodes-ComfyUI, install, restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/DemonAlone/DemonAlone-nodes-ComfyUI

then restart. Pure Python glue, no dependencies, no model downloads - available the moment the pack loads.

Common issues & troubleshooting

The socket refuses to connect. Both inputs need to actually be typed LIST - this pack's custom type, not a generic Python list from an unrelated node pack. If you're trying to feed in something from a different pack's list-handling nodes, it likely won't match unless that pack happens to use the identical type name.

I only have one list, do I need this node? No - this only matters once you have two separate lists to merge. A single list can be wired straight to whatever consumes it.

I need more than two lists combined. Chain two of these nodes: combine the first pair, then combine that result with a third list in a second List Combiner. There's no variadic version in this pack, so a three-or-more-way merge is a small chain rather than one node.

Output order looks wrong. Double-check which list is plugged into list_a versus list_b - it's easy to swap them by accident when rewiring, and since there's no sorting here, whatever order you feed in is exactly what comes out.